1. Field of the Invention
The present invention relates to a liquid silicone rubber coating composition that is ideal for producing air bags for vehicles and the like, wherein a film of a silicone rubber coating is formed on a fibrous fabric such as 6,6-nylon, 6-nylon or polyester, and is particularly suited to the production of curtain air bags, which unlike the air bags installed for the driver's seat and passenger seat, are housed along the edge of the roof from the front pillar, and must be capable of maintaining an inflated state for a certain period of time in order to protect the region around the head and prevent people being flung from the vehicle during a collision or rollover of the vehicle, and also relates to a curtain air bag having a silicone rubber coating layer comprising a cured product of such a composition, and a method of producing such an air bag.
2. Description of the Prior Art
Conventional air bag silicone rubber compositions used for forming a rubber coating on a fibrous fabric, include the compositions described below. For example, patent reference 1 discloses a liquid silicone rubber coating composition for an air bag that exhibits excellent adhesion to base fabrics, prepared by adding an inorganic filler, an organopolysiloxane resin, and an epoxy group-containing organosilicon compound to an addition curable composition. Patent reference 2 discloses a liquid silicone rubber coating composition for an air bag that develops excellent adhesion to base fabrics upon heat curing for a short period, prepared by adding an inorganic filler, an organopolysiloxane resin, an organotitanium compound, and an alkyl silicate or alkyl polysilicate to an addition curable composition. Patent reference 3 discloses a silicone rubber coating composition for an air bag with excellent thin-film coating properties, in which the viscosity of a vinyl group-containing organopolysiloxane is restricted to not more than 8,000 centipoise. Patent reference 4 discloses a liquid silicone rubber composition for coating that is used in the production of a silicone rubber-coated base fabric with reduced tackiness, and is prepared by adding a wet silica with an average BET specific surface area within a range from 150 to 250 m2/g and an average particle size of not more than 20 μm to a rubber coating composition.
However, when these compositions are used in curtain air bag applications, because all of the compositions suffer from inferior adhesion to the air bag base fabric, none of the compositions is able to satisfactorily suppress leakage of the inflator gas to enable the inflation time to be sustained for a satisfactory period.
Addition-curable compositions containing a zirconium compound which is related to the present invention are disclosed in Patent References 5 to 8. However, the zirconium compounds described as examples in these references are four-coordinate compounds, but oxyzirconium compounds used in the present invention are not disclosed therein.
[Patent Reference 1] U.S. Pat. No. 5,877,256
[Patent Reference 2] JP 2002-138249 A
[Patent Reference 3] JP 2001-287610 A
[Patent Reference 4] U.S. Pat. No. 6,387,520
[Patent Reference 5] U.S. Pat. No. 4,742,103
[Patent Reference 6] JP 4-178461 A
[Patent Reference 7] EP 0497349 A2
[Patent Reference 8] U.S. Pat. No. 5,625,022